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Yukon 3.75 gears for Ford 9 inch....noise

42K views 127 replies 13 participants last post by  LS1-IROC 
#1 ·
Make a long story short, I built my own housing to put a Ford 9 in a 1999 Camaro SS. The car is a stick and the stock rear was making noise, so after two gear changes in the stock 7.5 and all them making noise I decided to build a 9. Everything turned out real nice except now the 9 is making noise. I started with Richmond Excels, which I know the reputation Richmonds have for making noise. Of course they made noise as low 10 mph. So, I bought a set of Yukons. I have a set in the 8.5 10 bolt in my truck and they are silent. Anyway they are 1000 times better than the Richmonds but I still have a small whine on acel and decel. I started out with the same .019 pinion shim I had with the Richmonds and the pattern was too deep. So I started to bring the pinion out. I went to .021 all I had was a .010 and a .011 to add together, back lash at .006. It still looked too deep to me but I was out of shims and the next jump I could make would be .025 and it was to far out. I loaded up the center section and took it to a local machine shop. Jimmy Mattingly’s Machine Shop. He builds pulling tractor engines and is a major Ford guy. Anyway Jimmy told me to open the backlash up and that my pinion shim looks OK. He gave me a couple more shims a .012 and a .014. This time I opened the lash up to about .008 and put the .010 and the .012 in to give me .022. It looked pretty good to me but it seemed like the drive side was staying too deep and the coast was coming out more than the drive. So I went on and tried .011 and .012 to give me .023 and it looked like the coast was too far out and the drive was good. I put it together with .022 and about .008 back lash and it has a small whine. I am thinking about just unbolting the pinion and replacing the .010 with the .011 put it back .023. I figure the lash will open up a little more but should still be in spec. looking for some opinions on where to go. I am about done with rear ends.... :pain: I only put about 5 miles on the car for a test drive. I want to fix the noise so I don’t mess the gears up.

If you would like to see the 9 I built here is a link to it on LS1 tech

http://www.ls1tech.com/forums/gears-axles/1363354-building-junkyard-9-compared-8-8-a-4.html
 
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#103 ·
96lt4c4 said:
I dont know, I am begening to wonder if it is my housing. Not being straight and causing axels to bind. We did do a lot of welding on it.
I've seen your statements that the axles slid right in and out. If your housing was not straight it should be hard to get the axles in and out.

Have you double checked that your axles are the correct length for your housing?
 
#105 ·
prostreet6t9 said:
I've seen your statements that the axles slid right in and out. If your housing was not straight it should be hard to get the axles in and out.

Have you double checked that your axles are the correct length for your housing?
When I first got the axels one of them was a little to long, about 1/16 of the wheel bearing sticking out and the axel bottoming out on the carrier pin. So we put it in a lathe and cut about 1/8 off. I got paranoid about the driver side so I put a little red grease on the end of it and slid it in. I pulled it back out and there was some grease on the pin so I cut 1/16 of of it just to be safe. I did the grease trick on both of them again and they were not hitting anymore.

I am in the process of having a friend machine me some aluminum collars to make a jig to check the housing. I can get a 1.5" bar for about $70. At this point I am going to rule everything out before it goes back together. I cant afford to keep ruining ring and pinions.

Here is what I am planning on doing, if its straight then good, if not them I have to figure out how to straighten it.

http://www.crankshaftcoalition.com/wiki/Straightening_a_rear_end_housing
 
#106 ·
Just messing around tonight and stuck the axels in the housing with the posi between them to see how much play I had. There is just a little over an inch between the axels when they are all the way in the housing.

In the video you can see a little wobble in the posi when I spin it. Its really not that accurate because it is just kind of hanging there. I need to look up and see how much clearance should be between the 2 axels, I am not sure what it is suppose to be from the factory.

http://youtu.be/zW2ThQeX2eA



 
#107 ·
Looks like the factory width between the axels should be 1 1/8". Maybe one of the axels is still just a little too long and touching inside of the posi and causing an issue? I am grasping at straws.

Maybe I will get my bar today and see if it is straight.
 
#108 ·
96lt4c4 said:
Looks like the factory width between the axels should be 1 1/8". Maybe one of the axels is still just a little too long and touching inside of the posi and causing an issue? I am grasping at straws.

Maybe I will get my bar today and see if it is straight.
To measure correctly you will need to put a loaded center section into your housing. Run a tape down your tubes and hook it on the inside of the side gear. Measure to the lip in your housing end that the axle brg seats against.

Then you can measure your axle from the tip to the inside of the axle brg.
 
#110 ·
AutoGear said:
i admire your tenacity. I will admit Ive never had much experience doing rear axles other than class time in high school. However, aluminum housings don't inspire confidence in me. I would have dropped this off at a shop way before this point LOL

I am getting close to giving up. I have put the 7.5 10 bolt back in the car for the time being so that I can take my time trouble shooting the 9".
 
#111 ·
prostreet6t9 said:
To measure correctly you will need to put a loaded center section into your housing. Run a tape down your tubes and hook it on the inside of the side gear. Measure to the lip in your housing end that the axle brg seats against.

Then you can measure your axle from the tip to the inside of the axle brg.

When I measured I ran the tape in till it bottomed out on the carrier pin and measured to the outside of the housing end. My bearings are flush with the outside of the housing when they are all the way in. The GM backing plates are now my bearing retainers. It could very well be that one of my axels is still to long.
 
#112 ·
96lt4c4 said:
When I measured I ran the tape in till it bottomed out on the carrier pin and measured to the outside of the housing end. My bearings are flush with the outside of the housing when they are all the way in. The GM backing plates are now my bearing retainers. It could very well be that one of my axels is still to long.
For GOOD spline engagement you want the spline to fully go thru the side gear but not so far that the axle tip hits the pin. At this this point anything from the retainer out is not of concern. Your housing end will have a lip that the axle brg seats against.. Measure from the inside of the side gear to the lip that the axle brg seats against. Then measure your axle from the inside of the axle brg to the end.

If you wanted to use a measurement from the pin... Thats fine too. Just measure from the pin to the lip that the axle brg seats against. Then when measuring your axle from tip to inside of axle brg and that will tell you if its hitting the pin.

To be honest,I'm not sure that this is your problem. It just looked like you had checked just about everything else.

I build quite a few Aluminum housings and I dont have problems with them. So I really doubt the aluminum housing is causing your problem.
 
#113 ·
prostreet6t9 said:
For GOOD spline engagement you want the spline to fully go thru the side gear but not so far that the axle tip hits the pin. At this this point anything from the retainer out is not of concern. Your housing end will have a lip that the axle brg seats against.. Measure from the inside of the side gear to the lip that the axle brg seats against. Then measure your axle from the inside of the axle brg to the end.

If you wanted to use a measurement from the pin... Thats fine too. Just measure from the pin to the lip that the axle brg seats against. Then when measuring your axle from tip to inside of axle brg and that will tell you if its hitting the pin.

To be honest,I'm not sure that this is your problem. It just looked like you had checked just about everything else.

I build quite a few Aluminum housings and I dont have problems with them. So I really doubt the aluminum housing is causing your problem.

I am going to throw it in a center section tonight and re measure just to be sure. I have a small enought tape measure now that I can clip it on the side of the gears in the posi. I have narrowed it down to the, axels, housing, and posi. Those are the only things that have stayed the same threw all this. I need to post some pictures of the bearing races that came out of the carrier this time. I had to put new bearings on the posi to run it in the stock Ford case, I think they measure 2.891. The ones for the aluminum case are 3.062. Anyway the wear pattern on the new races is all over the place. The only have about 50 miles on them.
 
#115 ·
Thanks to prostreet6t9, I have finally found it. Just goes to show when you think things are right sometimes you just need to go back and double check.
Axels were too long and hitting inside the posi. I measured wrong. I bottomed my tape against the pin in the posi and I should have been clipping it on the side gears. I put everything in the old ford center section, stuck it in the housing and re measured. Both axels were a 1/16th too long. Just that little bit was causing it to hit the block in the center of the posi. I ground a good 1/16th off each axel and re taperd them by hand. They turned out pretty good.

I set up my new ring and pinion in the aluminum housing and now I think the posi is bent somewhere, the pattern was moving up and down the tooth as I spun it.













I am so burnt out on this thing that now even though I am pretty sure this is whats wrong with it, I do not want to work on it. :smash:

prostreet6t9, Thank you sir, I owe you a beer.
 
#118 ·
96lt4c4 said:
Thanks to prostreet6t9, I have finally found it. Just goes to show when you think things are right sometimes you just need to go back and double check.
Axels were too long and hitting inside the posi. I measured wrong. I bottomed my tape against the pin in the posi and I should have been clipping it on the side gears. I put everything in the old ford center section, stuck it in the housing and re measured. Both axels were a 1/16th too long. Just that little bit was causing it to hit the block in the center of the posi. I ground a good 1/16th off each axel and re taperd them by hand. They turned out pretty good.

I set up my new ring and pinion in the aluminum housing and now I think the posi is bent somewhere, the pattern was moving up and down the tooth as I spun it.



I am so burnt out on this thing that now even though I am pretty sure this is whats wrong with it, I do not want to work on it. :smash:

prostreet6t9, Thank you sir, I owe you a beer.
Your welcome :) Hopefully that was the problem. Like 302 says.... walk away for a bit :thumbup:
 
#119 ·
I've read through most of your post....I too am fighting some noise in my 9" in my IROC. I have not gone through all the steps you have, but I have played around with it quite a bit. I did not see if you said you checked for ring gear run-out. I have .003 runout on my ring gear when torqued to the Trac-loc posi. I beleive this is what my issue is. I have got it to the point where it's pretty quiet now...only whines between 50-70 mph on accel...quiet all the time on decel. Good luck with it!
 
#120 ·
prostreet6t9 said:
Your welcome :) Hopefully that was the problem. Like 302 says.... walk away for a bit :thumbup:

It has to be, I kept wondering where the metal was coming from. If you listen to the Youtube video at about 1:50 my phone falls between the back seat and the tunnel and you can hear metal to metal grinding sound. I am pretty sure that is what it is, it obviously isnt a good thing that they were hitting. One side was hitting bad enough to gall the block pretty good.

Anyway I took the posi to work with me yesterday. Luckilly I have accsess to some pretty cool tools. I spun the 2 halves of the posi in a lathe and checked for runout, we also have a machined flat slab of granite the is 10 foot long and 3 feet thick. I layed the 2 halves on the granite and tryed to slide a .001" shim stock underneath and it wouldnt go. The posi checked out fine. The only thing I found was that the threw bolts on the Yukon case were bent. I have a N Strange case that I am going to try.
 
#121 ·
Well, after all the checking on the posi, I still have a lot of run out on the ring gear. I think I have wore the area that the ring gear presses on to. I can put the ring gear on by hand, its not a press fit anymore. My new posi will be here today, hopefully that will fix it.
 
#122 ·
Got the posi tonight and was suprised at what I found. The Yukon and Ford Racing are the same posi. If you look on Yukons website the part number is the same as the part number on the Ford Racing posi that I just got from Summit Racing. When comparing the two units something just didnt look right....







The one on the left is the new one. Why in the hell would Quick Performance send my a posi with half of the hat machined off? From what I can tell there should be no clearence issues with the aluminum case. Even if there is I would much rather grind on the case a little then cut half the material off the side of the posi and make it weak. I thought the machine job on the posi looked like crap. I could tell that someone had put it in a lathe and turned it down. Now I can see how much they took off, and its a bunch! I am begening to wonder if the posi was flexing. Crazy.....
 
#125 ·
prostreet6t9 said:
Thats pretty common actually. Sometimes customers are hard to figure out and will gripe if they have to clearance the case if a thick hat is used. Other customers are fine with it. I personally always use the thick and do some grinding if needed.

I set it up last night and it clears the case but was hitting the billet cap. A flapper wheel on my grinder took care of that, no big deal at all. I didn’t have to remove much material. I would rather have some off the cap than a bunch off the posi. Still getting some run out on the ring gear though. I check both ring gear mating surfaces, spinning the posi and using a dial indicator and it is dead straight. It has to be coming from this ring and pinion. I go from one thing to another. My back lash is varying about .002 around the ring gear. What is acceptable? I know going through this I have had some with no run out. This is a new Motive performance 3.89 gear. I am thinking about sending it back to Summit and trying another one.
 
#126 ·
96lt4c4 said:
I set it up last night and it clears the case but was hitting the billet cap. A flapper wheel on my grinder took care of that, no big deal at all. I didn’t have to remove much material. I would rather have some off the cap than a bunch off the posi. Still getting some run out on the ring gear though. I check both ring gear mating surfaces, spinning the posi and using a dial indicator and it is dead straight. It has to be coming from this ring and pinion. I go from one thing to another. My back lash is varying about .002 around the ring gear. What is acceptable? I know going through this I have had some with no run out. This is a new Motive performance 3.89 gear. I am thinking about sending it back to Summit and trying another one.

If I was getting a .002 run out I would set the backlash at 8 at the tight spot putting you at 10 on the loose side,and check patterns.
 
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